Url: http://crop.scijournals.org/cgi/content/abstract/17/5/794
Frequency Distribution of Maize Yield Before and After Reciprocal
Recurrent Selection
1R. H. Moll, Abdul Bari and C. W. stuber2
Abstract
Reciprocal recurrent selection in populations of Zea mays L. will be of great value if the increase in mean performance isaccompanied by a corresponding increase in performance of hybridsfound in the upper tail of the genotypic distribution. We examined the frequency distributions for yields of two populations of single-cross hybrids. A population of 192 intercultivar singlecrosses among inbreds was derived from two cultivars, ‘Jarvis Golden Prolific’ and ‘Indian Chief’, aftersix cycles of reciprocal recurrent selection. This populationof single crosses was compared with a control population of185 single crosses among unselected inbreds from the original cultivars. Frequency distribution of average single-cross yieldsover replications and locations showed no significant deviationsfrom normal distributions. A small but statistically significantestimate of skewness was found for average yields of singlecrosses from the selected cultivar. Mean yields of single crossesfrom the selected cultivars averaged 12.5% greater than thosefrom the unselected cultivars. Variances among the selectedsingle crosses were smaller than among the unselected singlecrosses, but the differences were small and not statisticallysignificant. Reciprocal recurrent selection apparently had littleeffect on the distribution of single-cross yields other thanan increase in mean performance. This implied that the shapeof the distribution had not changed but that the distributionhad been shifted to the right, with an increased probabilityof outstanding hybrids in the upper tail. The best 10 singlecrosses from the selected population averaged 8.6% more yieldthan the 10 best single crosses from the original population. Five single crosses from the selected population exceeded the yield of the best single cross from the control population.
Key Words: Skewness • Kurtosis • Normal distribution • Single crosses
1
Contribution from the Dep. of Genetics, North Carolina StateUniv. Paper No. 5173 of the Journal series of the North CarolinaAgric. Exp. Stn., Raleigh, N.C. Partially supported by cooperativeagreement No. 12-14-100-10, 144 (34) between the North CarolinaAgric. Exp. Stn. and ARS-USDA, and a grant from DeKalb AgResearch,Inc.
2
Professor of genetics, North Carolina State Univ.; Leader, PlantGenetics and Breeding, Dep. of Agronomy, Institut PertanianBogor, Bogor, Indonesia; and research geneticist, ARS USDA,and professor of genetics, North Carolina State Univ., Raleigh,NC 27607, respectively.
